Niacin is an ancient myth. It does nothing to rid the body of THC.

Drinking a lot of water in the days/weeks before the test is of no help. THC is not water soluble (unlike certain other drugs), its fat soluble. However, the THC metabolites that are present in the bladder can be diluted (by drinking fluids) to where the urine sample registers below the cutoff thresholds of the drug screen. Its a balancing act and the actions are temporary - once all of the fluids taken in had been urinated out, a "dirty" donor will resume testing postive for THC. Therefore, drinking fluids is only helpful on the day of the U/A.

The proper vitamin to use is B2 (Riboflavin), which is only used to bring color back to urine during dilution protocols. It has no effect on ridding the body of THC.

There is no product that can permanently rid the body of THC. The only proven way to rid the body of THC is time and fat-burning exercise.